Abstract

The neurotransmitter receptor proteins are integral components
in the communication between adjacent cells of the nervous system, spanning
the width of the postsynaptic membrane and protruding into the synaptic cleft
and cell cytoplasm. They mediate the effects of neurotransmitters between
adjacent neurons.

The
principles of radioligand‐binding assays. The receptor (R) preparation and
radioligand (L) are incubated to equilibrium. The bound radioactivity is then
separated from the free, most frequently by rapid filtration. The bound
radioactivity thus yields a measure of the receptor present. Using
saturation‐binding curves and Scatchard transformation, the affinity of the
radioligand for the receptor can be determined.

Pertinent
features of G protein‐coupled neurotransmitter receptors. (a) The key
features, including the transmembrane topology of metabotropic G
protein‐coupled receptors. NT, N‐terminal; CT, C‐terminal; the solid
rectangles are the seven transmembrane domains; the red arrows point to
the sites of N‐glycosylation and the zig‐zag line represents the
palmitoylation at the C‐terminus. (b) The G protein‐coupled receptor as viewed
through the plane of the membrane.